The present invention relates to tube filling machines, and more particularly to tube holders used with such machines.
Laminated thermoplastic tubes are commonly used for product packaging containing viscous materials. The nozzle and shoulder insert are typically thicker and more rigidly structured than the attached tubular sidewalls providing structure for the dispensing end and shaping for the tube. For unfilled tubes, the circular shoulders particularly help maintain the circularity of the adjoining sidewalls before the tubes are filled, at least closer to the nozzle end. The opposite end of the tube remains open and provides an entry into the internal cavity for filling the tube with the product. After filling the open end may be closed by crimping or capping.
The unfilled tubes are typically packaged and transported in bulk to the filling machine. The packaged tubes may be considerably deformed particularly at the sidewall area proximate to the open end which lacks support from the tube shoulder. The open end may partially collapse inwards and assume an oval cross sectional shape in which the sidewalls of the tube are no longer straight and parallel. This resulting ovality may interfere with the tube filling operation and product feed nozzles which are inserted into the open end of the tube. Tube filling machines can generally only tolerate ovality on the order of about 10%. This can limit the selection of tube materials to more rigid ones and the tube making process.
The ability to maintain circularity of the tube at the filling station is desired to reduce or eliminate the foregoing limitations.